With the “in situ” method of extracting bitumen from oil sands using steam (e.g. Cyclic Steam Stimulation=CSS; Steam Assisted Gravity Drainage=SAGD), large quantities of water vapor are required for heating the bitumen in the deposit. Typically, steam at a temperature of 250° C. and having a quality of 0.95, i.e. in the almost superheated state, is used. Although this steam has a very high energy content, very large volumes of water accumulate and have to be pumped to the earth's surface again together with the oil and recovered there.
The use of additional electric heating of a reservoir is already described in DE 10 2007 008 292 A1 as well as in the earlier non-prior-published German patent applications of the applicant DE 10 2007 036 832, DE 10 2007 040 605 and DE 10 2007 040 607 and can be successfully demonstrated by means of mathematical simulations. Specifically in the case of the additional inductive heating proposed there, reference is made to the EM(Electromagnetic)-SAGD method.
However, the relatively high cost of electric power compared with the energy form “steam” reduces the economic advantage of the latter proposals.
Extraction of bitumen from oil sands with the assistance of electric heating-has not yet been employed commercially in a real-world application. In known pilot installations which employ purely electric, resistive heating the electric power is taken from the electricity grid.
The steam for SAGD or CSS methods is mostly generated in separate steam boilers which are typically fired by natural gas or bitumen. It has also been proposed to extract process steam for the above purpose from existing gas and steam installations whose electrical energy is fed into the power grid. These installations are therefore always arranged centrally and at a fixed location, and the transmission of the energy is associated with not insignificant losses.
Proceeding on this basis, it is an object of the invention to propose a method concept by means of which the cost-effectiveness of the already proposed method can be improved. Another object is to disclose an associated installation with corresponding operating method.